Sand blasting



July-13, 1943. J. N. VOEIRGE SAND BLASTING Filed Dec. 26, 1941 gAIIIIIIl-IIIIIII II IIII/lIIIIIIIII/I IIIIIII Patented July 13, 1943SAND BS'I'ING John Nicholas Voergc, Westmount, Quebec,

Application December 2d, 1941, Serial No. 424,511

(ill. Si -ll) @lalms.

This invention relates to sandblasting.

Objects It is a principal object of the invention to provide a method ofsandblasting embodying means to prevent the spread of the blast.

It is a further object oi the invention to provide a method in which theblasting abrasive can be recovered for further use.

It is a still further object to provide a simple and convenientapparatus for carryhig out this method.

In ordinary methods of sand blasting employ ing air as the propellantfluid, the abrasive material is after leaving the blasted surface, scat=tered about indiscriminately. As a consequence, the operator and othersin the vicinity of the operations are subjected to the danger orinhaling abrasive particles. Frequently, sandblasting op erators developsilicosis, or at least must ire quently be removed from the job lestthey do.

i To avoid these consequences, a method has been developed in whichwater is used to propel the sand. This has the disadvantages of bothreducing the sheet of the abrasive by wetting it before impact with theblasted surface and or" requiring high water pressure to operate.

By the present method these disadvantages are avoided and positiveadvantages provided as well. According to this method, a jet of sand ispropelled by air pressure from a centrally disposed nozzle and ablanketing screen of water projected outside the sand jet. The waterdoes not come into contact with the sand before the latter reaches itsobjective but the screen created by the water catches the sand and otherparticles rebounding from the treated surface. In this way, the sand isprevented from spreading and at the same time it is carried away in thewater stream so that it may be collected for re-use.

A preferred apparatus for carrying out this process is featured by acentral tube through which the sand is projected and a concentricallyarranged nozzle structure connected to this tube. This nozzle is adaptedto project a frustro-conical stream or sheet of water. Means areprovided in the nozzle for adjusting the velocity of the sheet while thetube through which the sand is carried may be made renewable to alloweasy replacement.

Drawing Having thus generally described the invention, reference willnow be made to the accompanying drawing which illustrates a preferredform of apparatus according to the invention, and in which:

Figure 1 is a fragmentary cross section through this preferred form ofapparatus.

Figure 2 is a horizontal cross section as along the line 22 of Figure l.

-Figure 3 is a frontal elevation of the device of Figuresl and 2.

Figure s is a reduced elevational view illustrating a portion oithedevice of the previous figures and the method of the presentinvention.

Referring more particularly to the drawing, the sand blast apparatus ismade up of a body A, for instance, a casting or otherwise formed part.This body is formed with a longitudinal central opening it receiving aremovable tube i i forming a passage for the sand or other blastingmaterial. A set screw it) extending through a boss 53 on the bodysecures the tube ii in place.

Mounted on the body A is a jacket is having 7 at one end outwardlyflared portions 66 forming control therefor.

a mouth. At the other end, the jacket it includes an annular flange iiengaging the body A. The body includes upstanding bosses 26 to which thejacket is screwed by means of set screws 2 l. The jacket it alsoincludes a threaded connection 25 constituting an inlet to which thethreaded end of a water pipe 26 is connected.

The forward end of the body is threaded as at he to receive a threadedfrustro-conical ring or plug iii. The ring 36' is adapted to cooperatewith the flared portions it of the Jacket 55 to form a nozzle and may bescrewed inwards or outwards to vary the clearance between its taperedface and the inner surfaces of the flared portions l8 whose taperapproximates that of the ring. A lock-nut 9% is provided to lock thering in the desired position.

Operation In operation, the tube ii is connected With a suitable sourceof sand and air pressure and a The jacket 15 is connected through thepipe 26 with a suitable source of water pressure and a control for thepressure. Thus connected, the device is ready for use in sand blastingfor the purpose of cleaning or conditioning surfaces to receive paint,etc. When both air and water pressures are turned on, the air-sand jet Cis projected substantially as noted in Figure 1 against the surface B tobe treated.

The water is projected in a conical sheet D about the sand blast.

V The sand is projected by the blast. and flying away from the surfaceis caught by the water sheet which carries it away in a stream fromwhich it may be recovered for further use.

The amount of pressure in the air line varies relative to the surfacebeing treated. For instance, in the case of blasting sandstone oralumimm: 20 to 50 lbs. per square inch pressure is satisfactory. Forsteel or hard stone the pressure required will be in the order of 80lbs. per square inch. It is not necessary to have heavy water pressureas the only function of the water is to form a screen to catch the blastparticles. A relatively low water pressure of 25 to 50 lbs. has beenfound satisfactory. It should be understood that these figures aremerely illustrative and are not to be taken in a limiting sense.

This method has great advantages. The sand does not come into contactwith water until after it has impinged on the surface being treated. Thesand can easily be recovered from the water stream which carries itaway.

High pressure water is not necessary. The only function of the water isto form a protective sheet to concentrate the blasting abrasive.

It will be understood that the word sand has been used for convenienceto express the abrasive material and that this term can be expanded bythe doctrine of equivalents to cover other abrasives which might be usedfor the same purpose. Similar remarks apply to th terms air and water.

Any suitable material can be chosen for the manufacture of the parts ofthe blasting apparatus. For instance, cast iron pipe has been foundsatisfactory for the sand-air line H as this material can be renewedfrequently at a low cost. l

Whil no pressure equipment or controls are shown in the drawing, it isunderstood that the method presumes the use of suitable plant togetherwith controls for regulating the flow of sand, air and water.

It will be understood that various modifications may be made in thisinvention without departing from the spirit thereof or the scope of theclaims, and therefore the exact forms shown are to be taken asillustrative only and not in a limiting sense, it being desired thatonly such limitations shall be placed thereon as may be imposed by thestate of the prior art or are set forth in the accompanying claims.

I claim:

1. A sandblast apparatus, comprising, a bodyhaving an inlet end and anoutlet end and a passage extending therebetween,v a liner adapted forcarrying sand and air removably mounted in said passage, a water jacketsurrounding at least a portion of said body and having a flared portionadjacent said outlet forming a conical -mouth, a frustro-conical plugconnected to said 10 body for axial movement in relation thereto, saidplug being adapted to form with the flared mouth of said jacket afrustro-conical water discharge nozzle of adjustable width, 0. watercommunication to said jacket, and a communication to said liner for sandand air.

2. A sandblast apparatus as claimed in claim 1 wherein said bodyincludes a threaded portion adjacent the discharge end and said plug isprovided with a corresponding threaded portion mating with the threadedportion of said body.

3. The method of sandblasting comprising projecting a stream ofsubstantially dry abrasive 4. The method of sandblasting comprisingprojecting a stream of substantially dry abrasive particles against asurface being treated, simultaneously projecting a co-extensivecontinuous substantially frustro-conical enclosing sheet of water,whereby a substantially transparent protective shield is formed aboutthe particle stream to entrain particles emanating from the surfacebeing treated.

5. The method of sandblasting comprising projecting a stream ofsubstantially dry abrasive particle against a portion of a surface beingtreated, simultaneously projecting a co-extensive continuous enclosingsheet of water against said surface in surrounding spaced relation tosaid portion being treated, whereby a substantially transparentprotective shield is formed about the particle stream from the source ofprojection of the abrasive particles to the surface being treated.

JOHN NICHOLAS VOERGE.

